Self-aligning pitman bearing box



Ma; i9, 1972s.

' ,538,318 v. L. FoRsYTH SELF ALIGNING ,PITMAN BEARING BOX Filel May 51. 1924 Patented May 19, 1925.

UNITEDsT-ATES PATENT OFFICE.

VALOR-1S L. FORSYTH, OF FORT WORTH, TEXAS.

SELF-A LIGNING PITMAN BEARXNG BOX'.

Application filed May 31,

To ZZ fio/1.0m t may concern.'

Be it known that I, VALonrs L. Fonsr'rI-I, citizen ot the United States, residing at Fort Worth, in the county of Tarrantfand State of Texas, have invented'certain new. and usetul Improvements in Self-Aligning` Pitman Bearing Boxes, of which the follow'- ing is a specification.

This invention relates to nen7 and useful in'iprovements in self-aligning pitmen bearing boxes. Y

The invention has particularly to 4do with, pitmen which are used in connection with the Walking beams of well drilling rigs and pumps. These pitmen have considerable' length and there is more or less play, with the result that the Wrist pin Works under an undue strain and is Jfrequently lbent or broken.

The object of the invention is to provide ink the pitman, a bearing box. for the Wrist pin, mounted to rock or move so as to aline its bearing surfaces with the pin a-nd thus' compensate variations in the alignment of the pitman. v

A further object is to provide a bearing box having means `for snugly adjusting its bearing members to the pin, thus taking up Wear and arranged to move bodily with the pin so as not to bind, twist or break the latter, when the pitman is moved out of line; also whereby the pin is not subjected to distortion. in its bearing and a free Working is thus obtained.

A construction designed to carry out the invention together with other novel features. will be hereinafter described.

The invention will be more readily understood from a reading of the following specification and by reference to the accompanying drawings in Which an example ofthe invention is shown and wherein:

Fig. 1 is a side elevational' apitman constructed in accordancek with my invention, Fig. 2 is a front elevation of the same, 'Fig'. 3 is a vertical sectional view on the line 3-3 of Fig. 1, and

Fig. t is a cross-sectional view on the line 4-4 of Fig. 1.

In the drawings the numeral 10 designates a tubular pitman which is 'flattened to exhibit an elliptical yshape in cross-section. At its upper end the pitman has a stirrup 11 by which it is suspended from the end of the Walking beam (not shown). Near the lower end the pitman has opposite rectan- 1924. Serial NG. 716,931..

guiar openings 12 tl'irough Which the ends ota bearing box project. Thi'sbox comprises an upper member 13 and a lower member .1st divided at the center of the box. Each member has a semi-cyclindrical seat 15" or receiving a bearing member 16 of suitable metal. 'lhe members 16 when assembled provide a cylindrical bore or bearing surface. The details of the foregoing parts may vary according to the conditions of use and manufacture. l

ln order that the box may rock or oscillate the lower member has a reduced boss 17 disposed transversely of the bore of the bearing` members 16. The boss has a longitudinal concaved recess 18 in its under surface, whereby the boss may fulcrum on a pin 19 extending transversely through the pitman and suitably secured therein. Suthcient clearance inthe openings 12 around the box is provided so that the box may rock freely. y

A; Wrist pin 20 of the usual .construction has its collar 21 bearing against the end of the box. For holding the members of the box together a. Wedge 29. is passed through slots 23 in the pitman parallel to the pin 19. The upper member 13 of the box has a transverse groove 24 provided with a convex bottom cut on a radius having its center coincident with the center of the pin 19. The under edge of the Wedge is curved to conform to the contour ot the bottoml of the groove.

rlhe Wedge is driven in to hold the box and its bearing members vin contact With the wrist pin 2O and a Cotter pin Qris passed through one of a series ot holes 2G in the Wedge to keep the latter in place. It Will be seen that the box may roclc on the pin 19 because the-,bottom ot the groove 24 ,will ride under the Wedge. This oscillation will be ample to compensate for any variation of the pitman from its perpendicular position with relation to the Wrist pin. It is obvious that the bearing box is adequately supported and a `proper bearing is had for the wrist pin 20'. Vhenever the pitman is distorted the box will retain its aligmnent with the Wrist pin 20, thus avoiding` undue Jfriction, strains and breaks.

Various changes in the size and shape ot the parts may be made Within the scope of the appended claims. The pitman need not be tubular or fiattened. but may be othervise constructed to receive the box.

IVhut I claim, is:

l. The combination with a pitman having openings in its opposite sides, of o wrist pin box extending through said openings, zi fulerum support for the lower portion of the box on which said box is mounted to rook, and means for coniining Said box on its fulcrum support and holding it in position in the pitman.

2. The combination with a pitmun having openings in its opposite Sides, of i Wrist pin box extending through Said openings, a, liulerum Support for the lower portion of the box on which said box is mounted to rock, and u fastening device in the pitmnn With which the upper portion of the box has rocking engagement.

3. The combination with a pitinan having openings in its opposite sides, of n divided bearing box for a Wrist pin, a boss on the if lower end of the box, a transverse pin in the pitman on which the boss is fulerumecl, the upper end of the box hzufing a convex groove, und u Wedge mounted in the pitnmn and engaging in said groove which has a Width greater than the thickness of the Wedge.

In testimony whereof I affix my Signature.

VALGRIS L. FORSYTH. 

